82 lines
2.9 KiB
Markdown
82 lines
2.9 KiB
Markdown
# Basketball Website
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Welcome to Basketball Website on Exercism's Elixir Track.
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If you need help running the tests or submitting your code, check out `HELP.md`.
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If you get stuck on the exercise, check out `HINTS.md`, but try and solve it without using those first :)
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## Introduction
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## Access Behaviour
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Elixir uses code _Behaviours_ to provide common generic interfaces while facilitating specific implementations for each module which implements it. One such common example is the _Access Behaviour_.
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The _Access Behaviour_ provides a common interface for retrieving data from a key-based data structure. The _Access Behaviour_ is implemented for maps and keyword lists, but let's look at its use for maps to get a feel for it. _Access Behaviour_ specifies that when you have a map, you may follow it with _square brackets_ and then use the key to retrieve the value associated with that key.
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```elixir
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# Suppose we have these two maps defined (note the difference in the key type)
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my_map = %{key: "my value"}
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your_map = %{"key" => "your value"}
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# Obtain the value using the Access Behaviour
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my_map[:key] == "my value"
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your_map[:key] == nil
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your_map["key"] == "your value"
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```
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If the key does not exist in the data structure, then `nil` is returned. This can be a source of unintended behavior, because it does not raise an error. Note that `nil` itself implements the Access Behaviour and always returns `nil` for any key.
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## Instructions
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You are working with a web development team to maintain a website for a local basketball team. The web development team is less familiar with Elixir and is asking for a function to be able to extract data from a series of nested maps to facilitate rapid development.
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## 1. Extract data from a nested map structure
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Implement the `extract_from_path/2` function to take two arguments:
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- `data`: a nested map structure with data about the basketball team.
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- `path`: a string consisting of period-delimited keys to obtain the value associated with the last key.
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If the value or the key does not exist at any point in the path, `nil` should be returned
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```elixir
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data = %{
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"team_mascot" => %{
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"animal" => "bear",
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"actor" => %{
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"first_name" => "Noel"
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}
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}
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}
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BasketballWebsite.extract_from_path(data, "team_mascot.animal")
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# => "bear"
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BasketballWebsite.extract_from_path(data, "team_mascot.colors")
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# => nil
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```
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Use the _Access Behaviour_ when implementing this function.
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Do not use any `Map` or `Kernel` module functions for working with the nested map data structure.
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## 2. Refactor using included functions
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Your coworker reviewing your code tells you about a `Kernel` module function which does something very similar to your implementation.
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Implement `get_in_path/2` to use this `Kernel` module function.
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The arguments expected are the same as part 1.
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```elixir
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BasketballWebsite.get_in_path(data, "team_mascot.actor.first_name")
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# => "Noel"
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```
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## Source
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### Created by
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- @neenjaw
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### Contributed to by
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- @angelikatyborska
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- @NobbZ |